U.S. patent application number 17/127504 was filed with the patent office on 2022-05-05 for variable energy management methods and systems.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. The applicant listed for this patent is HONEYWELL INTERNATIONAL INC.. Invention is credited to Rajesh Chaubey, Daniel E. Lewis.
Application Number | 20220139234 17/127504 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-05 |
United States Patent
Application |
20220139234 |
Kind Code |
A1 |
Chaubey; Rajesh ; et
al. |
May 5, 2022 |
VARIABLE ENERGY MANAGEMENT METHODS AND SYSTEMS
Abstract
Methods and systems are provided for assisting operation of a
vehicle deviating from a desired manner of operation, such as an
aircraft deviating from a planned trajectory. One method involves
identifying a current aircraft altitude, identifying a current
aircraft configuration, determining a recommended flight path from
the current aircraft altitude for satisfying an upcoming constraint
associated with a reference descent strategy based at least in part
on the current aircraft configuration in response to a deviation
between the current aircraft altitude a target altitude according
to the reference descent strategy, and providing an output
influenced by the recommended flight path. The recommended flight
path includes a recommended vertical profile and a recommended
speed profile, and the recommended flight path is configured to
vary at least one of a kinetic energy or a potential energy of the
aircraft along the recommended flight path en route to the upcoming
constraint.
Inventors: |
Chaubey; Rajesh; (Bangalore,
IN) ; Lewis; Daniel E.; (Glendale, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONEYWELL INTERNATIONAL INC. |
Charlotte |
NC |
US |
|
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
Charlotte
NC
|
Appl. No.: |
17/127504 |
Filed: |
December 18, 2020 |
International
Class: |
G08G 5/00 20060101
G08G005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2020 |
IN |
202011047237 |
Claims
1. A method of assisting operation of an aircraft en route to an
airport, the method comprising: identifying a current altitude for
the aircraft; identifying a current configuration of the aircraft;
and in response to a deviation between the current altitude for the
aircraft and a target altitude according to a reference descent
strategy, determining a recommended flight path for satisfying an
upcoming constraint associated with the reference descent strategy
from the current altitude based at least in part on the current
configuration, wherein: the recommended flight path comprises a
recommended vertical profile and a recommended speed profile; and
the recommended flight path is configured to vary at least one of a
kinetic energy or a potential energy of the aircraft along the
recommended flight path en route to the upcoming constraint; and
providing an output influenced by the recommended flight path.
2. The method of claim 1, wherein determining the recommended
flight path comprises: identifying a variable energy management
strategy for the recommended flight path based on the deviation;
and incrementally generating a sequence of segments configured to
recapture the reference descent strategy forward from a current
location of the aircraft using the variable energy management
strategy.
3. The method of claim 2, wherein incrementally generating the
sequence comprises, for each segment of the sequence of segments:
determining a constraining value for a variable energy management
parameter associated with the variable energy management strategy
based at least in part on an aircraft drag configuration at the
start of the respective segment and a respective deviation from the
reference descent strategy at the start of the respective segment;
and determining a respective combination of a vertical profile and
a speed profile for the respective segment configured to reduce the
respective deviation from the reference descent strategy and
achieve the constraining value for the variable energy management
parameter.
4. The method of claim 3, wherein: identifying the variable energy
management strategy comprises identifying a variable vertical speed
energy management strategy for the recommended flight path based on
the deviation when the current altitude is below the target
altitude; determining the constraining value comprises determining
a minimum descent rate for the respective segment; and the
respective combination of a vertical profile and a speed profile
for the respective segment is configured to achieve the minimum
descent rate for the respective segment.
5. The method of claim 3, wherein: identifying the variable energy
management strategy comprises identifying a variable energy sharing
management strategy for the recommended flight path based on the
deviation when the current altitude is above the target altitude;
determining the constraining value comprises determining an energy
sharing ratio for a relationship between a first change in the
potential energy and a second change in the kinetic energy for the
respective segment; and the respective combination of a vertical
profile and a speed profile for the respective segment is
configured to achieve the energy sharing ratio along the respective
segment.
6. The method of claim 3, wherein: identifying the variable energy
management strategy comprises identifying a variable deceleration
rate management strategy for the recommended flight path;
determining the constraining value comprises determining a maximum
deceleration rate for the respective segment; and the respective
combination of a vertical profile and a speed profile for the
respective segment is configured to achieve the maximum
deceleration rate for the respective segment.
7. The method of claim 2, wherein the recommended vertical profile
is configured to vary a flight path angle along the sequence of
segments.
8. The method of claim 2, wherein a slope of the recommended speed
profile varies along the sequence of segments.
9. The method of claim 1, wherein the recommended vertical profile
and the recommended speed profile are cooperatively configured to
vary at least one of the kinetic energy or the potential energy of
the aircraft along the recommended flight path en route to the
upcoming constraint by varying at least one of a vertical speed of
the aircraft, a deceleration rate of the aircraft, and a ratio of
the potential energy to the kinetic energy of the aircraft along
the recommended flight path.
10. The method of claim 1, wherein providing the output comprises
displaying a graphical representation of at least one of the
recommended vertical profile and the recommended speed profile with
respect to a graphical representation of the reference descent
strategy.
11. The method of claim 1, wherein: providing the output comprises
providing, by a flight management system (FMS), the recommended
vertical profile and the recommended speed profile to a flight
control system (FCS); and the FCS autonomously operates the
aircraft in accordance with the recommended vertical profile and
the recommended speed profile.
12. A method of assisting operation of an aircraft to recapture an
optimal trajectory en route to an airport, wherein the optimal
trajectory satisfies a constraint in advance of the airport, the
method comprising: identifying a current energy state for the
aircraft at a current location of the aircraft; identifying a
current drag configuration of the aircraft; determining a variable
energy management strategy for reducing a deviation between the
current energy state and a target energy state at the current
location according to the optimal trajectory based on the
deviation; iteratively constructing a recommended flight path for
recapturing the optimal trajectory forward from the current
location using the variable energy management strategy, the
recommended flight path comprising a sequence of segments, wherein
iteratively constructing the recommended flight path comprises:
determining a constraining value for a variable energy management
parameter associated with the variable energy management strategy
based at least in part on an aircraft drag configuration at the
start of the respective segment and a respective deviation from the
optimal trajectory at the start of the respective segment; and
optimizing a respective vertical profile and a respective speed
profile for the respective segment to achieve the constraining
value for the variable energy management parameter based at least
in part on the aircraft drag configuration at the start of the
respective segment; and outputting indication of the recommended
flight path, wherein a flight path angle defined by the respective
vertical profiles for the sequence of segments varies along the
recommended flight path prior to recapturing the optimal
trajectory.
13. The method of claim 12, wherein: determining the variable
energy management strategy comprises identifying a variable
vertical speed energy management strategy when a current aircraft
altitude at the current location is below a target aircraft
altitude at the current location according to the optimal
trajectory; determining the constraining value comprises
calculating a minimum descent rate for the respective segment based
at least in part on the aircraft drag configuration at the start of
the respective segment and a respective deviation between an
aircraft altitude at the start of the respective segment and the
optimal trajectory at the start of the respective segment; and the
respective vertical profile and the respective speed profile for
the respective segment result in the minimum descent rate for the
respective segment.
14. The method of claim 12, wherein: determining the variable
energy management strategy comprises identifying a variable
deceleration rate energy management strategy when a current
aircraft speed at the current location is above a target aircraft
speed at the current location according to the optimal trajectory;
determining the constraining value comprises calculating a maximum
deceleration rate for the respective segment based at least in part
on the aircraft drag configuration at the start of the respective
segment and a respective deviation between an aircraft speed at the
start of the respective segment and the optimal trajectory at the
start of the respective segment; and the respective vertical
profile and the respective speed profile for the respective segment
are optimized for the maximum deceleration rate for the respective
segment.
15. The method of claim 12, wherein: determining the variable
energy management strategy comprises identifying a variable energy
sharing strategy when a current aircraft altitude at the current
location is above a target aircraft altitude at the current
location according to the optimal trajectory; determining the
constraining value comprises calculating a maximum ratio for a
decrease in potential energy with respect to a decrease in kinetic
energy for the respective segment based at least in part on the
aircraft drag configuration at the start of the respective segment
and a respective deviation between an aircraft altitude at the
start of the respective segment and the optimal trajectory at the
start of the respective segment; and the respective vertical
profile and the respective speed profile for the respective segment
are configured to achieve the maximum ratio for the decrease in
potential energy with respect to the decrease in kinetic energy for
the respective segment.
16. The method of claim 15, further comprising: identifying a
variable deceleration rate energy management strategy when a
current aircraft speed at the current location is above a target
aircraft speed at the current location according to the optimal
trajectory; calculating a maximum deceleration rate for each
respective segment based at least in part on the aircraft drag
configuration at the start of the respective segment and a
respective deviation between an aircraft speed at the start of the
respective segment and the optimal trajectory at the start of the
respective segment; and the respective vertical profile and the
respective speed profile for the respective segment are configured
to concurrently achieve the maximum deceleration rate and the
maximum ratio for the decrease in potential energy with respect to
the decrease in kinetic energy for the respective segment.
17. The method of claim 12, wherein outputting the indication of
the recommended flight path comprises a flight management system
(FMS) providing the respective vertical profiles and the respective
speed profiles for the sequence of segments to a flight control
system (FCS) for autonomous operation in accordance with the
respective vertical profiles and the respective speed profiles.
18. The method of claim 12, wherein outputting the indication of
the recommended flight path comprises displaying graphical
representations of the respective vertical profiles and the
respective speed profiles for the sequence of segments on a display
device with respect to graphical representations of an optimal
vertical profile and an optimal speed profile for the optimal
trajectory.
19. An aircraft system comprising: a navigation system to provide a
current altitude of an aircraft; a data storage element to maintain
one or more constraints defining a flight plan for the aircraft;
and a flight management system coupled to the navigation system and
the data storage element to determine a reference trajectory based
at least in part on the one or more constraints, identify a
variable energy management strategy for reducing a difference
between the current altitude and a target altitude according to the
reference trajectory based on the difference, and generate a
recommended flight path for recapturing the reference trajectory
using the variable energy management strategy, wherein: the
recommended flight path comprises a sequence of segments; each
segment of the sequence of segments has a respective vertical
profile and a respective speed profile associated therewith; and
the respective vertical profile and the respective speed profile
associated with the respective segment are configured to achieve a
constraining value determined for a variable energy management
parameter associated with the identified variable energy management
strategy.
20. The aircraft system of claim 19, wherein: the variable energy
management parameter comprises at least one of a vertical speed, a
deceleration rate, and an energy sharing ratio; and the
constraining value for the at least one of the vertical speed, the
deceleration rate, and the energy sharing ratio varies across the
sequence of segments.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Indian Provisional
Patent Application No. 202011047237, filed Oct. 29, 2020, the
entire content of which is incorporated by reference herein.
TECHNICAL FIELD
[0002] The subject matter described herein relates generally to
vehicle systems, and more particularly, embodiments of the subject
matter relate to aircraft systems that facilitate energy management
for recapturing a desired trajectory while maintaining compliance
with applicable constraints.
BACKGROUND
[0003] Often, it is desirable to operate an aircraft in stable
manner when descending and approaching an airport in order to land
safely and avoid hard landings or other actions that could increase
stress on the aircraft, which may increase maintenance or
inspection costs. Additionally, altitude constraints, speed
constraints, and the like may be provided by airport procedures,
air traffic control (ATC), or the like in order to improve flight
safety and/or manage air traffic. However, the various altitude,
speed, and other stability constraints typically do not account for
operating costs. Accordingly, a flight management system (FMS) is
often utilized to determine a cost-efficient or optimal trajectory
that satisfies the applicable altitude, speed, and stability
constraints using a cost function or cost index that accounts for a
variety of different factors (e.g., fuel remaining, aircraft
weight, meteorological conditions, and the like). In practice,
however, various circumstances such as adverse weather conditions,
on-board malfunctions, low quality of air traffic control, bad crew
cooperation, fatigue, visual illusions, inexperienced crew members,
and the like can result in the aircraft deviating from the
FMS-computed trajectory and risking stability or noncompliance with
required constraints, which could compromise safety.
[0004] Various techniques have been developed to help facilitate
stabilization when an aircraft deviates from an originally-planned
trajectory. However, existing approaches generally require a pilot
manually operate the aircraft and determine how to restore
stability and comply with other constraints, without guidance for
how to restore the originally-planned trajectory, and which results
in increased fuel consumption, noise, or other costs relative to
the originally-planned trajectory. Accordingly, it desirable to
provide guidance or automation that facilitates cost optimization
by recapturing an originally-planned trajectory and managing
aircraft energy for compliance with upcoming constraints.
BRIEF SUMMARY
[0005] Methods and systems are provided for assisting operation of
a vehicle, such as an aircraft. One method for assisting operation
of an aircraft en route to an airport involves identifying a
current altitude for the aircraft, identifying a current
configuration of the aircraft, in response to a deviation between
the current altitude for the aircraft and a target altitude
according to a reference descent strategy, determining a
recommended flight path for satisfying an upcoming constraint
associated with the reference descent strategy from the current
altitude based at least in part on the current configuration, and
providing an output influenced by the recommended flight path. The
recommended flight path includes a recommended vertical profile and
a recommended speed profile, and the recommended flight path is
configured to vary at least one of a kinetic energy or a potential
energy of the aircraft along the recommended flight path en route
to the upcoming constraint.
[0006] In another embodiment, method of assisting operation of an
aircraft to recapture an optimal trajectory en route to an airport
is provided. The optimal trajectory is configured to satisfy a
constraint in advance of the airport. The method involves
identifying a current energy state for the aircraft at a current
location of the aircraft, identifying a current drag configuration
of the aircraft, determining a variable energy management strategy
for reducing a deviation between the current energy state and a
target energy state at the current location according to the
optimal trajectory based on the deviation, iteratively constructing
a recommended flight path for recapturing the optimal trajectory
forward from the current location using the variable energy
management strategy, and outputting indication of the recommended
flight path, wherein a flight path angle defined by the respective
vertical profiles for the sequence of segments varies along the
recommended flight path prior to recapturing the optimal
trajectory. The recommended flight path includes a sequence of
segments, wherein iteratively constructing the recommended flight
path comprises determining a constraining value for a variable
energy management parameter associated with the variable energy
management strategy based at least in part on an aircraft drag
configuration at the start of the respective segment and a
respective deviation from the optimal trajectory at the start of
the respective segment and optimizing a respective vertical profile
and a respective speed profile for the respective segment to
achieve the constraining value for the variable energy management
parameter based at least in part on the aircraft drag configuration
at the start of the respective segment.
[0007] In another embodiment, an aircraft system is provided. The
aircraft system includes a navigation system to provide a current
altitude of an aircraft, a data storage element to maintain one or
more constraints defining a flight plan for the aircraft, and a
flight management system coupled to the navigation system and the
data storage element to determine a reference trajectory based at
least in part on the one or more constraints, identify a variable
energy management strategy for reducing a difference between the
current altitude and a target altitude according to the reference
trajectory based on the difference, and generate a recommended
flight path for recapturing the reference trajectory using the
variable energy management strategy. The recommended flight path
comprises a sequence of segments, each segment of the sequence of
segments has a respective vertical profile and a respective speed
profile associated therewith, and the respective vertical profile
and the respective speed profile associated with the respective
segment are configured to achieve a constraining value determined
for a variable energy management parameter associated with the
identified variable energy management strategy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Embodiments of the subject matter will hereinafter be
described in conjunction with the following drawing figures,
wherein like numerals denote like elements, and:
[0009] FIG. 1 is a block diagram of a system for an aircraft in one
or more exemplary embodiments;
[0010] FIG. 2 is a block diagram of a trajectory projection system
suitable for use with the aircraft of FIG. 1 in one or more
exemplary embodiments;
[0011] FIG. 3 is a flow diagram of an exemplary variable energy
management process suitable for use with the trajectory projection
system of FIG. 2 or the aircraft in the system of FIG. 1 in
accordance with one or more embodiments; and
[0012] FIGS. 4-5 depicts graphs of exemplary flight paths
constructed in accordance with the variable energy management
process in accordance with one or more exemplary embodiments.
DETAILED DESCRIPTION
[0013] Embodiments of the subject matter described herein generally
relate to systems and methods for recapturing a previously-planned
trajectory by managing energy to improve compliance with upcoming
constraints. While the subject matter described herein could be
utilized in various applications or in the context of various types
of vehicles (e.g., automobiles, marine vessels, trains, or the
like), exemplary embodiments are described herein in the context of
an aircraft. In particular, the subject matter is described
primarily in the context of a piloted or manned aircraft, although
it should be appreciated the subject matter can be implemented in
an equivalent manner for unmanned aerial vehicles, urban air
mobility vehicles, helicopters, rotorcraft, and the like.
[0014] As described in greater detail below, exemplary embodiments
described herein determine a recommended flight path from the
current position of the aircraft for recapturing a
previously-planned reference descent strategy and a satisfying an
upcoming constraint associated with the reference descent strategy
by varying the kinetic energy or potential energy of the aircraft
en route to the upcoming constraint. In exemplary embodiments, the
previously-planned reference descent strategy is realized as an
optimal descent strategy that includes an altitude profile (or
vertical profile) and a speed profile that were calculated or
otherwise determined by a flight management system (FMS) to satisfy
any applicable altitude, speed, required time of arrival (RTA)
and/or stabilization constraints. For example, an FMS-computed
optimal vertical descent profile may be configured to result in the
aircraft arriving at a desired horizontal or lateral ground
distance ahead of its destination landing location (e.g., a
stabilization distance) at an altitude, airspeed and aircraft
configuration (e.g., a stable energy state) that allow adequate
dissipation of the remaining aircraft energy during final approach,
touchdown and rollout. In one or more embodiments, the altitude and
speed profiles computed by the FMS may also be optimized in
accordance with a cost function or otherwise configured to achieve
a desired cost index value.
[0015] Based on the deviation between the current aircraft altitude
and/or the current aircraft speed at the current aircraft position
along the planned lateral trajectory for the aircraft and the
targeted aircraft altitude and/or the targeted aircraft speed at
the current aircraft position along the planned lateral trajectory,
one or more energy management strategies are identified for
reducing the deviation between the current aircraft state and the
targeted aircraft state according to the reference descent
strategy. Using the one or more identified energy management
strategies, the recommended flight path is incrementally
constructed forward from the current aircraft state as a sequence
of segments in a piecewise manner until intersecting the reference
descent strategy. Each segment of the recommended flight path is
defined by an altitude profile and a corresponding speed profile
that are configured to adjust the potential energy and/or kinetic
energy of the aircraft along that segment at a rate that is
determined on a per-segment basis. As a result, the rate at which
any given segment of the recommended flight path is configured to
adjust the potential energy and/or kinetic energy of the aircraft
while traversing that segment may be different from the rate(s) of
energy adjustment for the preceding and/or following segment(s),
such that the potential energy and/or kinetic energy increase or
decrease at variable rates along the recommended flight path.
[0016] The resulting sequence of altitude and speed profile
segments for the recommended flight path may be utilized to
autonomously operate the aircraft to recapture the reference
descent strategy or to otherwise provide strategic guidance to a
pilot operating the aircraft. In this regard, an autonomous
operating mode may be utilized to resolve the deviation(s) and
recapture the reference descent strategy and satisfy upcoming
constraints in situations where the current aircraft state may
otherwise be considered to be too high, too low, too fast, and/or
too slow to satisfy the upcoming constraint or otherwise achieve an
optimal descent strategy, that is, situations where a pilot
manually flying the aircraft may be unable to intuitively ascertain
how to operate the aircraft to satisfy the constraints.
[0017] FIG. 1 depicts an exemplary embodiment of a system 100 which
may be located onboard a vehicle, such as an aircraft 102. The
system 100 includes, without limitation, a display device 104, a
user input device 106, a processing system 108, a display system
110, a communications system 112, a navigation system 114, a flight
management system (FMS) 116, a flight control system (FCS) 118, one
or more avionics systems 120, and one or more data storage elements
124 cooperatively configured to support operation of the system
100, as described in greater detail below.
[0018] In exemplary embodiments, the display device 104 is realized
as an electronic display capable of graphically displaying flight
information or other data associated with operation of the aircraft
102 under control of the display system 110 and/or processing
system 108. In this regard, the display device 104 is coupled to
the display system 110 and the processing system 108, and the
processing system 108 and the display system 110 are cooperatively
configured to display, render, or otherwise convey one or more
graphical representations or images associated with operation of
the aircraft 102 on the display device 104, as described in greater
detail below.
[0019] The user input device 106 is coupled to the processing
system 108, and the user input device 106 and the processing system
108 are cooperatively configured to allow a user (e.g., a pilot,
co-pilot, or crew member) to interact with the display device 104
and/or other elements of the aircraft system 100. Depending on the
embodiment, the user input device 106 may be realized as a keypad,
touchpad, keyboard, mouse, touch panel (or touchscreen), joystick,
knob, line select key or another suitable device adapted to receive
input from a user. In some embodiments, the user input device 106
is realized as an audio input device, such as a microphone, audio
transducer, audio sensor, or the like, that is adapted to allow a
user to provide audio input to the aircraft system 100 in a "hands
free" manner without requiring the user to move his or her hands,
eyes and/or head to interact with the aircraft system 100.
[0020] The processing system 108 generally represents the hardware,
circuitry, processing logic, and/or other components configured to
facilitate communications and/or interaction between the elements
of the aircraft system 100 and perform additional processes, tasks
and/or functions to support operation of the aircraft system 100,
as described in greater detail below. Depending on the embodiment,
the processing system 108 may be implemented or realized with a
general purpose processor, a controller, a microprocessor, a
microcontroller, a content addressable memory, a digital signal
processor, an application specific integrated circuit, a field
programmable gate array, any suitable programmable logic device,
discrete gate or transistor logic, processing core, discrete
hardware components, or any combination thereof, designed to
perform the functions described herein. In practice, the processing
system 108 includes processing logic that may be configured to
carry out the functions, techniques, and processing tasks
associated with the operation of the aircraft system 100 described
in greater detail below. Furthermore, the steps of a method or
algorithm described in connection with the embodiments disclosed
herein may be embodied directly in hardware, in firmware, in a
software module executed by the processing system 108, or in any
practical combination thereof. In accordance with one or more
embodiments, the processing system 108 includes or otherwise
accesses a data storage element 124, such as a memory (e.g., RAM
memory, ROM memory, flash memory, registers, a hard disk, or the
like) or another suitable non-transitory short or long term storage
media capable of storing computer-executable programming
instructions or other data for execution that, when read and
executed by the processing system 108, cause the processing system
108 to execute and perform one or more of the processes, tasks,
operations, and/or functions described herein.
[0021] The display system 110 generally represents the hardware,
firmware, processing logic and/or other components configured to
control the display and/or rendering of one or more displays
pertaining to operation of the aircraft 102 and/or systems 112,
114, 116, 118, 120 on the display device 104 (e.g., synthetic
vision displays, navigational maps, and the like). In this regard,
the display system 110 may access or include one or more databases
122 suitably configured to support operations of the display system
110, such as, for example, a terrain database, an obstacle
database, a navigational database, a geopolitical database, a
terminal airspace database, a special use airspace database, or
other information for rendering and/or displaying navigational maps
and/or other content on the display device 104. In this regard, in
addition to including a graphical representation of terrain, a
navigational map displayed on the display device 104 may include
graphical representations of navigational reference points (e.g.,
waypoints, navigational aids, distance measuring equipment (DMEs),
very high frequency omnidirectional radio ranges (VORs), and the
like), designated special use airspaces, obstacles, and the like
overlying the terrain on the map. In one or more exemplary
embodiments, the display system 110 accesses a synthetic vision
terrain database 122 that includes positional (e.g., latitude and
longitude), altitudinal, and other attribute information (e.g.,
terrain type information, such as water, land area, or the like)
for the terrain, obstacles, and other features to support rendering
a three-dimensional conformal synthetic perspective view of the
terrain proximate the aircraft 102.
[0022] In the illustrated embodiment, the processing system 108 is
also coupled to the communications system 112, which is configured
to support communications to and/or from the aircraft 102 via a
communications network. For example, the communications system 112
may also include a data link system or another suitable radio
communication system that supports communications between the
aircraft 102 and one or more external monitoring systems, air
traffic control, and/or another command center or ground location.
In this regard, the communications system 112 may allow the
aircraft 102 to receive information that would otherwise be
unavailable to the pilot and/or co-pilot using the onboard systems
114, 116, 118, 120. For example, the communications system 112 may
receive meteorological information from an external weather
monitoring system, such as a Doppler radar monitoring system, a
convective forecast system (e.g., a collaborative convective
forecast product (CCFP) or national convective weather forecast
(NCWF) system), an infrared satellite system, or the like, that is
capable of providing information pertaining to the type, location
and/or severity of precipitation, icing, turbulence, convection,
cloud cover, wind shear, wind speed, lightning, freezing levels,
cyclonic activity, thunderstorms, or the like along with other
weather advisories, warnings, and/or watches. The meteorological
information provided by an external weather monitoring system may
also include forecast meteorological data that is generated based
on historical trends and/or other weather observations, and may
include forecasted meteorological data for geographical areas that
are beyond the range of any weather detection systems 120 onboard
the aircraft 102. In other embodiments, the processing system 108
may store or otherwise maintain historical meteorological data
previously received from an external weather monitoring system,
with the processing system 108 calculating or otherwise determining
forecast meteorological for geographic areas of interest to the
aircraft 102 based on the stored meteorological data and the
current (or most recently received) meteorological data from the
external weather monitoring system. In this regard, the
meteorological information from the external weather monitoring
system may be operationally used to obtain a "big picture"
strategic view of the current weather phenomena and trends in its
changes in intensity and/or movement with respect to prospective
operation of the aircraft 102.
[0023] Still referring to FIG. 1, in an exemplary embodiment, the
processing system 108 is coupled to the navigation system 114,
which is configured to provide real-time navigational data and/or
information regarding operation of the aircraft 102. The navigation
system 114 may be realized as a global positioning system (GPS),
inertial reference system (IRS), or a radio-based navigation system
(e.g., VHF omni-directional radio range (VOR) or long range aid to
navigation (LORAN)), and may include one or more navigational
radios or other sensors suitably configured to support operation of
the navigation system 114, as will be appreciated in the art. The
navigation system 114 is capable of obtaining and/or determining
the instantaneous position of the aircraft 102, that is, the
current (or instantaneous) location of the aircraft 102 (e.g., the
current latitude and longitude) and the current (or instantaneous)
altitude (or above ground level) for the aircraft 102. The
navigation system 114 is also capable of obtaining or otherwise
determining the heading of the aircraft 102 (i.e., the direction
the aircraft is traveling in relative to some reference).
Additionally, in an exemplary embodiment, the navigation system 114
includes inertial reference sensors capable of obtaining or
otherwise determining the attitude or orientation (e.g., the pitch,
roll, and yaw, heading) of the aircraft 102 relative to earth.
[0024] In an exemplary embodiment, the processing system 108 is
also coupled to the FMS 116, which is coupled to the navigation
system 114, the communications system 112, the flight control
system 118, and one or more additional avionics systems 120 to
support navigation, flight planning, and other aircraft control
functions in a conventional manner, as well as to provide real-time
data and/or information regarding the operational status of the
aircraft 102 to the processing system 108. It should be noted that
although FIG. 1 depicts a single avionics system 120, in practice,
the aircraft system 100 and/or aircraft 102 will likely include
numerous avionics systems for obtaining and/or providing real-time
flight-related information that may be displayed on the display
device 104 or otherwise provided to a user (e.g., a pilot, a
co-pilot, or crew member). For example, practical embodiments of
the aircraft system 100 and/or aircraft 102 will likely include one
or more of the following avionics systems suitably configured to
support operation of the aircraft 102: a weather system, an air
traffic management system, a radar system, a traffic avoidance
system, an autopilot system, an autothrust system, hydraulics
systems, pneumatics systems, environmental systems, electrical
systems, engine systems, trim systems, lighting systems, crew
alerting systems, electronic checklist systems, detection systems,
an electronic flight bag and/or another suitable avionics
system.
[0025] Still referring to FIG. 1, the flight control system 118
generally represents the component(s) of the aircraft 102 that are
coupled to the FMS 116 and one or more of the other onboard systems
108, 110, 112, 114, 120 to receive or otherwise obtain a lateral
trajectory and corresponding altitude and speed profiles from the
FMS 116 and autonomously operate the aircraft 102 in accordance
with the FMS-computed trajectories. For example, the FMS 116 may
store or otherwise maintain a sequence of waypoints or procedures
that define a planned route for a flight plan, along with other
altitude, speed and/or RTA constraints that may be defined for the
flight plan. The constraints be entered manually by the pilot,
coded as part of a procedure to be flown as part of the flight
plan, and/or assigned by air traffic control. The FMS 116
calculates or otherwise determines a lateral trajectory for the
flight plan utilizing the waypoints and/or procedures defined for
the flight plan, and calculates or otherwise determines a vertical
profile for the aircraft 102 to fly for the lateral trajectory
defined by the flight plan that satisfies applicable altitude
constraints using aircraft performance predictions, expected
meteorological information or other environmental factors, and
potentially other constraints or criteria. The FMS 116 constructs a
vertical profile that satisfies the relevant altitude constraints,
which define windows that the aircraft 102 may pass through
vertically while traveling the lateral trajectory. In conjunction
with the lateral trajectory and vertical profile, the FMS 116
calculates or otherwise determines a speed profile that satisfies
any relevant speed constraints and/or RTA constraints and achieves
a desired aircraft performance (e.g., an input cost index value).
The FMS 116 then outputs or otherwise provides commands or other
indicia of the planned lateral trajectory and the optimal vertical
profile and speed profile to be flown to the FCS 118 for
implementation.
[0026] In one or more embodiments, the FCS 118 includes flight
director, an autopilot system (or autopilot), and a thrust
management system (or thrust manager). The flight director
generally represents a process, service, software or firmware
component that is executed, generated or otherwise implemented by
the FCS 118 to autonomously command or otherwise control operation
of the autopilot and the thrust manager in accordance with an
autonomous operating mode that has been selected or otherwise
activated. In this regard, the autopilot generally represents the
process, service, software or firmware component that is executed,
generated or otherwise implemented by the FCS 118 to autonomously
command or otherwise control operation of the flight control
surfaces of the aircraft 102 to regulate the pitch of the aircraft
102 to achieve a desired flight path angle and/or vertical speed
and regulate the roll of the aircraft 102 to achieve a desired
lateral trajectory. The deceleration rate manager 214 generally
represents the process, service, software or firmware component
that is executed, generated or otherwise implemented by the FCS 118
to autonomously command or otherwise control operation of the
engines to regulate the speed or thrust produced and achieve the
targeted speed profile. For example, when a vertical navigation
(VNAV) autonomous operating mode is selected or otherwise
activated, the flight director utilizes the vertical profile
provided by the FMS 116 to generate corresponding commands or
instructions for the autopilot and the thrust manager to
autonomously operate the aircraft 102 in accordance with the
vertical profile and speed profile provided by the FMS 116, thereby
satisfying any applicable altitude constraints, speed constraints,
or other criteria or conditions of the flight plan. It should be
noted that there are numerous different autonomous operating modes
that may be supported by the FCS 118 and/or the flight director,
and the subject matter described herein is not limited to any
particular type, number, or combination of autonomous operating
modes that may be supported.
[0027] It should be understood that FIG. 1 is a simplified
representation of the aircraft system 100 for purposes of
explanation and ease of description, and FIG. 1 is not intended to
limit the application or scope of the subject matter described
herein in any way. It should be appreciated that although FIG. 1
shows the display device 104, the user input device 106, and the
processing system 108 as being located onboard the aircraft 102
(e.g., in the cockpit), in practice, one or more of the display
device 104, the user input device 106, and/or the processing system
108 may be located outside the aircraft 102 (e.g., on the ground as
part of an air traffic control center or another command center)
and communicatively coupled to the remaining elements of the
aircraft system 100 (e.g., via a data link and/or communications
system 112). In this regard, in some embodiments, the display
device 104, the user input device 106, and/or the processing system
108 may be implemented as an electronic flight bag that is separate
from the aircraft 102 but capable of being communicatively coupled
to the other elements of the aircraft system 100 when onboard the
aircraft 102. Similarly, in some embodiments, the data storage
element 124 may be located outside the aircraft 102 and
communicatively coupled to the processing system 108 via a data
link and/or communications system 112. Furthermore, practical
embodiments of the aircraft system 100 and/or aircraft 102 will
include numerous other devices and components for providing
additional functions and features, as will be appreciated in the
art. In this regard, it will be appreciated that although FIG. 1
shows a single display device 104, in practice, additional display
devices may be present onboard the aircraft 102. Additionally, it
should be noted that in other embodiments, various features and/or
functionality of processing system 108 described herein (or a
subset of features and/or functionality described in the context of
the processing system 108) can be implemented by or otherwise
integrated with the features and/or functionality provided by the
display system 110, the FMS 116 and/or another onboard avionics
system 120 (e.g., flight control system), or vice versa. In other
words, some embodiments may integrate the processing system 108
with the display system 110, the FMS 116, the FCS 118 or another
onboard avionics system 120; that is, the processing system 108 may
be a component of the display system 110, the FMS 116, the FCS 118
or another onboard avionics system 120.
[0028] FIG. 2 depicts an exemplary embodiment of a trajectory
projection system 200 suitable for use with an aircraft, such as
aircraft 102 of FIG. 1. The illustrated trajectory projection
system 200 includes, without limitation, a FMS 202 (e.g., FMS 116)
and a data storage element 204 (e.g., data storage element 124)
that stores or otherwise maintains the various constraints 206 that
define a flight plan to be flown by an aircraft. In this regard,
the flight plan constraints 206 include information identifying the
procedures or waypoints and their corresponding geographic
locations (e.g., latitude and longitude coordinates) that define
the lateral route to be flown by the aircraft, along with
information identifying any altitude constraints associated with
various waypoints of the flight plan (e.g., the type of altitude
constraint and the constraining altitude value for a respective
waypoint), information identifying any speed constraints associated
with various waypoints of the flight plan (e.g., the type of speed
constraint and the constraining speed value for a respective
waypoint), and information identifying any RTA constraints
associated with various waypoints of the flight plan (e.g., the
required time of arrival for a respective waypoint). The flight
plan constraints 206 may also include stabilization constraints or
criteria, such as, for example, a geographical location of a
stabilization target point, an aircraft configuration state
associated with the stabilization target point (e.g., landing gear
extended, predefined flap angle, speedbrakes retracted, etc.), a
target speed or target speed range at the stabilization target
point, a maximum descent rate associated with the stabilization
target point, and/or the like. For example, U.S. Patent Publication
No. 2013/0218374 provides an exemplary list of stabilization
criteria upon reaching a stabilization target point corresponding
to a position along an approach that is 1000 feet above ground
level (for instrument meteorological conditions) or 500 feet above
ground level (for visual meteorological conditions).
[0029] In the illustrated embodiment, the FMS 202 includes a
trajectory generation system (or trajectory generator) 210, which
generally represents a process, service, software or firmware
component that is executed, generated or otherwise implemented by
the FMS 202 to compute, calculate, or otherwise determine a planned
lateral trajectory for the aircraft for flying the flight plan
defined by the constraints 206 along with corresponding vertical
profiles and speed profiles for the aircraft that are configured to
satisfy the altitude, speed, RTA, stabilization, and/or other
constraints associated with the flight plan. In this regard, the
trajectory generator 210 may utilize one or more aerodynamic models
to model or otherwise predict the performance of the aircraft along
the planned lateral trajectory as a function of the aircraft gross
weight, fuel remaining, forecasted and/or expected meteorological
conditions along the route and calculate or otherwise determine
corresponding vertical and speed profiles for the planned lateral
trajectory that satisfy the applicable altitude, speed, RTA and/or
stabilization flight plan constraints 206. In exemplary
embodiments, the vertical profile and the speed profile are
optimized to minimize the value of a cost function or otherwise
achieve a desired cost index, as will be appreciated in the art. In
this regard, the initial vertical profile and speed profile output
by the trajectory generator 210 represent the optimal manner in
which the planned lateral trajectory should be flown to achieve the
desired tradeoffs between fuel consumption, travel time, noise,
and/or the like. The planned lateral trajectory, the optimized
vertical profile and the optimized speed profile determined by the
trajectory generator 210 may be output or otherwise provided by the
FMS 202 to a flight control system (e.g., FCS 118) for autonomously
operating the aircraft, as will be appreciated in the art.
[0030] As described in greater detail below in the context of FIG.
3, in exemplary embodiments, the FMS 202 continually or
periodically monitors the current state of the aircraft (e.g.,
output to the FMS 116, 202 by the navigation system 114) for
deviations from the optimal vertical profile and/or the optimal
speed profile. Based on the nature of the deviation(s), the
trajectory generator 210 is configured to generate, construct, or
otherwise determine a recommended flight path for reducing the
deviation(s) and recapturing the optimal vertical profile and the
optimal speed profile while satisfying upcoming flight plan
constraints by varying the potential and/or kinetic energy of the
aircraft in accordance with one or more energy management
strategies. In this regard, the FMS 202 includes a vertical speed
management system (or vertical speed manager) 212 configured to
support a variable vertical speed of the aircraft along the
recommended flight path, a deceleration rate energy management
system (or deceleration rate manager) 214 configured to support a
variable deceleration rate along the recommended flight path, and
an energy sharing management system (or energy sharing manager) 216
configured to support a variable ratio of the change in potential
energy to the change in kinetic energy along the recommended flight
path.
[0031] The vertical speed manager 212 generally represents the
process, service, software or firmware component that is executed,
generated or otherwise implemented by the FMS 202 to calculate or
otherwise determine a vertical speed value on a per-segment basis
based on inputs pertaining to the current aircraft state, with the
respective vertical speed values being utilized by the trajectory
generator 210 to incrementally construct the recommended flight
path forward from the current aircraft state when the current
altitude of the aircraft is below the targeted altitude for the
current aircraft location according to the optimal vertical
profile. In this regard, the vertical speed value output by the
vertical speed manager 212 represents the minimum descent rate (or
minimum downward vertical speed) achievable for the aircraft for
the given segment, which, in turn, may be utilized to by the
trajectory generator 210 to calculate or otherwise determine
altitude and speed profiles that minimize the vertical speed in
descent to reduce the altitude difference between the aircraft
altitude and the optimal aircraft altitude according to the optimal
vertical profile. In exemplary embodiments, the vertical speed
value output by the vertical speed manager 212 is calculated or
otherwise determined based on the altitude difference between the
current altitude of the aircraft at the start of the respective
segment and the targeted altitude for the aircraft at that location
according to the optimal vertical profile, the current or expected
drag configuration of the aircraft at the start of the respective
segment, and the current or expected weight of the aircraft at the
start of the respective segment. The calculated vertical speed
value may also be influenced by the meteorological conditions
associated with the segment and any difference between the current
speed of the aircraft at the start of the respective segment and
the targeted speed according to the optimal speed profile. For
example, when the current speed of the aircraft at the start of the
respective segment is less than the targeted speed according to the
optimal speed profile, the calculated vertical speed value may
account for the increase in thrust needed to reduce the speed
deviation over the length of the segment, or vice versa.
[0032] The deceleration rate manager 214 generally represents the
process, service, software or firmware component that is executed,
generated or otherwise implemented by the FMS 202 to calculate or
otherwise determine a maximum deceleration rate value on a
per-segment basis based on inputs pertaining to the current
aircraft state, with the respective maximum deceleration rate
values being utilized by the trajectory generator 210 to
incrementally construct the recommended flight path forward from
the current aircraft state when the current speed of the aircraft
is above the targeted speed for the current aircraft location
according to the optimal speed profile. In this regard, the maximum
deceleration rate value output by the deceleration rate manager 214
represents the maximum deceleration rate achievable for the
aircraft for the given segment, which, in turn, may be utilized to
by the trajectory generator 210 to calculate or otherwise determine
altitude and speed profiles that reduce the deviation(s) between
the current aircraft energy state and the optimal aircraft energy
state according to the optimal vertical and speed profiles.
Conversely, in other scenarios, when the current speed of the
aircraft is above the targeted speed for the current aircraft
location according to the optimal speed profile, the deceleration
rate manager 214 may be configured to calculate or otherwise
determine a maximum acceleration rate value (or minimum
deceleration rate) on a per-segment basis based on inputs
pertaining to the current aircraft state, with the respective
maximum acceleration rate values being utilized by the trajectory
generator 210 to incrementally construct the recommended flight
path forward from the current aircraft state. In exemplary
embodiments, the maximum deceleration rate value output by the
vertical speed manager 212 is calculated or otherwise determined
based on the difference between the current speed of the aircraft
at the start of the respective segment and the targeted speed
according to the optimal speed profile, the current or expected
drag configuration of the aircraft at the start of the respective
segment, the current or expected airbrake setting or configuration
at the start of the respective segment, and the current or expected
weight of the aircraft at the start of the respective segment.
[0033] The energy sharing manager 216 generally represents the
process, service, software or firmware component that is executed,
generated or otherwise implemented by the FMS 202 to calculate or
otherwise determine a maximum energy sharing ratio on a per-segment
basis based on inputs pertaining to the current aircraft state,
with the respective maximum energy sharing ratio being utilized by
the trajectory generator 210 to incrementally construct the
recommended flight path forward from the current aircraft state
when the current altitude of the aircraft is above the targeted
altitude for the current aircraft location according to the optimal
vertical profile. In this regard, the maximum energy sharing ratio
represents the maximum achievable ratio for the reduction in
potential energy of the aircraft (e.g., via changing the flight
path angle or pitch to reduce altitude) with respect to a
corresponding reduction in kinetic energy of the aircraft (e.g.,
via airbrakes, an increased drag configuration, a headwinds, and/or
the like). In exemplary embodiments, the energy sharing ratio value
output by the energy sharing manager 216 is calculated or otherwise
determined based on the difference between the current speed of the
aircraft at the start of the respective segment and the targeted
speed according to the optimal speed profile, the current or
expected drag configuration of the aircraft at the start of the
respective segment, the current or expected airbrake setting or
configuration at the start of the respective segment, and the
current or expected weight of the aircraft at the start of the
respective segment. For example, the energy sharing manager 216 may
be configured to determine the amount of change in altitude is
required to support a desired change in airspeed over the length of
the segment based on the various inputs to the energy sharing
manager 216 and the length of the respective segment. For example,
if the length of the segment is two nautical miles and the amount
of speed to be reduced over the segment is ten knots, the energy
sharing manager 216 calculates or otherwise determines an energy
sharing ratio that is configured to alter the altitude by an amount
that achieves the desired speed reduction (e.g., by altering the
rate of descent to decrease or increase the amount of potential
energy transferred to kinetic energy).
[0034] When the aircraft is descending (e.g., in a descent or
approach flight phase), the FMS 202 is configured to initiate or
otherwise trigger the trajectory generator 210 determining a
recommended flight path for recapturing the reference descent
strategy defined by the optimal vertical and speed profiles in
response to a deviation between the current aircraft energy state
and the targeted energy state for the current location of the
aircraft according to the reference descent strategy. Based on the
current state of the aircraft with respect to the reference descent
strategy, the FMS 202 and/or the trajectory generator 210
identifies or otherwise determines which of the energy management
strategies corresponding to the different management systems 212,
214, 216 should be utilized for recapturing the reference descent
strategy. After identifying the energy management strategies to be
utilized, the trajectory generator 210 constructs a recommended
flight path for recapturing the reference descent strategy in a
piecewise manner forward from the current aircraft location until
intercepting the reference descent strategy. For each segment, the
trajectory generator 210 provides current or expected values for
aircraft state parameters or variables at the start of the
respective segment to the identified energy management system 212,
214, 216, which, in turn, calculates or otherwise determines the
constraining value for the respective energy management parameter
associated with that energy management system 212, 214, 216 to be
utilized for constructing the respective segment.
[0035] For example, when the current aircraft altitude is below the
targeted altitude for the reference descent strategy, the vertical
speed manager 212 may provide the minimum vertical speed for
descending from the current aircraft altitude (e.g., based on the
current aircraft drag configuration, the current aircraft weight,
and the like), which, in turn, may be utilized by the trajectory
generator 210 to determine a corresponding altitude and speed
profile for the length of the initial segment from the current
aircraft location that achieves that minimum downward vertical
speed (or minimum descent rate) using aerodynamic models, aircraft
performance predictions, meteorological information for the
segment, and/or the like. When the initial segment does not result
in recapturing the reference descent strategy, the trajectory
generator 210 may input or otherwise provide the expected state of
the aircraft at the end of that initial segment (e.g., the expected
aircraft drag configuration, the predicted aircraft weight, and the
like) to the vertical speed manager 212, which provides the minimum
vertical speed for descending along the next segment of the
recommended flight path. In this regard, the minimum vertical speed
for the second segment of the recommended flight path may vary or
otherwise be different from the minimum vertical speed utilized to
construct the initial segment of the recommended flight path. In a
similar manner, the trajectory generator 210 determines
corresponding altitude and speed profiles for the length of the
second segment starting from the end of the initial segment that
achieves its determined minimum downward vertical speed (or minimum
descent rate) using aerodynamic models, aircraft performance
predictions, meteorological information for the segment, and/or the
like. The trajectory generator 210 repeats incrementally
constructing segments forward until recapturing the reference
descent strategy.
[0036] Referring now to FIG. 3, in one or more exemplary
embodiments, a FMS or another component of an aircraft system is
configured to support a variable energy management process 300 to
provide guidance for managing an aircraft energy state and/or
autonomously operating an aircraft to return to a targeted energy
state in compliance with flight plan constraints. The various
tasks, functions, and operations described below as being performed
in connection with the illustrated process 300 may be implemented
using hardware, firmware, software executed by processing
circuitry, or any combination thereof. For illustrative purposes,
the following description may refer to elements mentioned above in
connection with FIGS. 1-2. In practice, portions of the variable
energy management process 300 may be performed by different
elements of an aircraft system 100, such as, for example, the
processing system 108, the display system 110, the navigation
system 114, the FMS 116, 202, the FCS 118, and/or other onboard
avionics system(s) 120. It should be appreciated that the variable
energy management process 300 may include any number of additional
or alternative tasks, the tasks need not be performed in the
illustrated order and/or the tasks may be performed concurrently,
and/or the variable energy management process 300 may be
incorporated into a more comprehensive procedure or process having
additional functionality not described in detail herein. Moreover,
one or more of the tasks shown and described in the context of FIG.
3 could be omitted from a practical embodiment of the variable
energy management process 300 as long as the intended overall
functionality remains intact.
[0037] Referring to FIG. 3, and with continued reference to FIGS.
1-2, in exemplary embodiments, the illustrated variable energy
management process 300 initializes or otherwise begins in response
to a deviation from an originally-planned trajectory for the
aircraft 102 while the aircraft 102 is in a descent or approach
flight phase. For example, a pilot may manually operate an aircraft
102 to deviate from an originally-planned trajectory based on
meteorological conditions, ATC instructions, air traffic or
collision avoidance warnings, and/or the like. As described above,
in exemplary embodiments, the originally-planned trajectory is
realized as an optimal descent strategy determined by a FMS 116,
202 using a cost function or cost index that includes an optimal
vertical profile configured to satisfy any altitude constraints or
other stabilization constraints associated with a flight plan for
the aircraft 102 and an optimal speed profile configured to satisfy
any speed constraints, RTA constraints, and/or other stabilization
constraints associated with the flight plan for the aircraft 102.
Thus, the optimal descent strategy provides a reference for the
aircraft trajectory that achieves the desired tradeoffs between
fuel consumption, travel time, noise, passenger comfort, and/or the
like while also satisfying stabilization criteria and other
safety-related constraints. In this regard, the variable energy
management process 300 may be performed to provide guidance to the
pilot for how to manually fly the aircraft 102 to recapture the
originally-planned descent strategy or to allow the pilot to engage
an autonomous operating mode that can autonomously operate the
aircraft 102 to recapture the originally-planned descent strategy,
and thereby achieve the desired cost minimization or efficiency of
operation.
[0038] The variable energy management process 300 identifies or
otherwise one or more variable energy management strategies to be
utilized to recapture the reference descent strategy based on the
deviation between the current energy state of the aircraft and the
targeted energy state for the aircraft at the current location of
the aircraft according to the reference descent strategy (task
302). In this regard, the variable energy management strategy (or
combination thereof) varies depending on the nature of the
difference between the current aircraft energy state and the
targeted energy state, that is, whether the current aircraft
altitude is too high or too low and/or whether the current aircraft
speed is too fast or too slow. When the current aircraft altitude
is below the targeted altitude according to the vertical profile
for the optimal descent strategy at the current aircraft location,
the FMS 116, 202 and/or the processing system 108 identifies the
variable vertical speed energy management strategy corresponding to
the vertical speed manager 212 as a variable energy management
strategy to be utilized to recapture the optimal vertical profile.
If the current aircraft speed is also above the targeted speed
according to the speed profile for the optimal descent strategy at
the current aircraft location, the FMS 116, 202 and/or the
processing system 108 identifies the variable deceleration rate
energy management strategy corresponding to the deceleration rate
manager 214 as a variable energy management strategy to be utilized
to recapture the optimal speed profile in concert with the variable
vertical speed energy management strategy. Conversely, when the
current aircraft altitude is above the targeted altitude according
to the vertical profile for the optimal descent strategy at the
current aircraft location, the FMS 116, 202 and/or the processing
system 108 identifies the variable energy sharing strategy
corresponding to the energy sharing manager 216 as a variable
energy management strategy to be utilized in concert with the
variable deceleration rate energy management strategy corresponding
to the deceleration rate manager 214 to recapture the optimal
vertical profile. On the other hand, when the current aircraft
altitude is at the targeted altitude but the current aircraft speed
is above the targeted speed according to the speed profile for the
optimal descent strategy, the FMS 116, 202 and/or the processing
system 108 identifies the variable deceleration rate energy
management strategy corresponding to the deceleration rate manager
214 as a variable energy management strategy to be utilized to
recapture the optimal speed profile. Conversely, when the current
aircraft speed is below the targeted speed according to the speed
profile for the optimal descent strategy, the FMS 116, 202 and/or
the processing system 108 identifies the variable deceleration rate
energy management strategy corresponding to the deceleration rate
manager 214 as a variable energy management strategy to be utilized
to recapture the optimal speed profile, with the deceleration rate
manager 214 outputting a maximum acceleration rate (or minimum
deceleration rate) for a respective segment when the difference
between the current aircraft speed and the targeted aircraft speed
is negative.
[0039] After identifying the variable energy management strategy or
combination of variable energy management strategies to be utilized
to mitigate the current aircraft energy state deviation(s) and
recapture the reference descent strategy, the variable energy
management process 300 identifies or otherwise obtains the current
aircraft drag configuration (task 304). In this regard, the FMS
116, 202 and/or the processing system 108 identifies the current
flap extension position, the current landing gear position, and the
current airbrake setting. The variable energy management process
300 also identifies or otherwise obtains the current gross weight
of the aircraft (task 306). For example, the FMS 116, 202 and/or
the processing system 108 may obtain the current amount of fuel
remaining onboard the aircraft 102, and then calculate or otherwise
determine an estimate for the current gross weight of the aircraft
based on the current amount of fuel remaining.
[0040] After identifying the current aircraft drag configuration
and current aircraft gross weight, the variable energy management
process 300 incrementally constructs segments for the recommended
flight path for recapturing the reference descent strategy forward
from the current aircraft position using the one or more variable
energy management strategies identified based on the current energy
state deviation(s) (task 308). In this regard, the trajectory
generator 210 determines a sequence of navigational segments for
incrementally operating the aircraft 102 in accordance with the
applicable variable energy management strategies until the
recommended flight path intercepts the reference descent strategy.
In one or more exemplary embodiments, the navigational segments
have a fixed length; that said, it should be noted the subject
matter described herein is not limited to fixed length navigational
segments and can be implemented in an equivalent manner using
variable length navigational segments. Additionally, it should be
noted that the navigational segments that define the recommended
flight path are not necessarily associated with any waypoints or
other navigational reference points of the flight plan.
[0041] For the initial segment of the recommended flight path, the
trajectory generator 210 inputs or otherwise provides, to the
identified ones of the variable energy management systems 212, 214,
216 information characterizing the current state of the aircraft
102 at the start of the segment, including, for example, the
current drag configuration of the aircraft 102, the current gross
weight of the aircraft 102, the current speed of the aircraft 102,
the current difference (if any) between the current speed of the
aircraft 102 and the targeted speed for the aircraft 102 according
to the optimal speed profile for originally-planned reference
descent strategy, and the current difference (if any) between the
current altitude of the aircraft 102 and the targeted altitude for
the aircraft 102 according to the optimal vertical profile for
originally-planned reference descent strategy. Based on the input
information, the respective variable energy management system 212,
214, 216 calculates or otherwise determines a constraining value
for its associated energy management parameter for the upcoming
segment that is output back to the trajectory generator 210 for use
in constructing the segment. In this regard, the trajectory
generator 210 utilizes the constraining value(s) provided by the
identified variable energy management system(s) 212, 214, 216 to be
utilized for a respective segment to determine the corresponding
changes in aircraft altitude, airspeed, and the like that achieve
the constraining value.
[0042] In exemplary embodiments, the variable energy management
systems 212, 214, 216 utilize the current aircraft speed and
current drag configuration to identify or otherwise determine
whether a drag configuration change should occur based on the
allowed aircraft speeds for the current drag configuration and/or
the next drag configuration (e.g., the maximum and/or minimum
allowed speeds for the respective drag configuration). In this
regard, for situations where the current aircraft altitude is below
the target altitude and/or the current aircraft speed is below the
targeted aircraft speed, the variable energy management systems
212, 214, 216 may be configured to delay a transition to the next
drag configuration until reaching the minimum allowable aircraft
speed for the current drag configuration. Conversely, for
situations where the current aircraft altitude is above the target
altitude and/or the current aircraft speed is above the targeted
aircraft speed, the variable energy management systems 212, 214,
216 may be configured to advance a transition to the next drag
configuration once the maximum allowable aircraft speed for the
next drag configuration is reached. Based on the current drag
configuration and/or the expected drag configuration change and the
other input parameters received from the trajectory generator 210,
the variable energy management systems 212, 214, 216 calculate or
otherwise determine the output value for its associated energy
management parameter for the upcoming segment that minimizes and/or
maximizes the reduction in the aircraft energy over the segment
according to the nature of the deviations between the current
aircraft energy state and the targeted energy state.
[0043] Based on the constraining energy management parameter values
and configuration change indicia (if any) output by the variable
energy management systems 212, 214, 216, the trajectory generator
210 constructs or otherwise generates corresponding speed and
altitude profiles for the segment, for example, by optimizing the
flight path angle and the speed profile to achieve the constraining
energy management parameter value using the appropriate drag
configuration(s) for the segment. In this regard, the trajectory
generator 210 utilizes one or more aerodynamic models to model or
otherwise predict the performance of the aircraft along the planned
lateral trajectory as a function of the current aircraft gross
weight at the start of the segment, the current fuel remaining at
the start of the segment, any forecasted and/or expected
meteorological conditions along the segment, and then varies or
otherwise optimizes the vertical and speed profiles for the fixed
length segment that satisfy the constraining energy management
parameter values output by the variable energy management systems
212, 214, 216. The resulting vertical and speed profiles may then
be utilized to define the initial segment of the recommended flight
path for recapturing the reference descent strategy. In some
embodiments, the trajectory generator 210 may utilize any
applicable altitude, speed, RTA, and/or other constraints along the
respective segment to arrive at the optimal vertical and speed
profiles that satisfy (or do not violate) any of the
constraints.
[0044] After determining vertical and speed profiles for the
initial segment, the trajectory generator 210 iteratively repeats
the process of providing, to the identified ones of the variable
energy management systems 212, 214, 216, information characterizing
the expected state of the aircraft 102 at the start of the segment
to be constructed, obtaining updated output values for the energy
management parameter values associated with the respective variable
energy management systems 212, 214, 216 for the segment to be
constructed, and then optimizing the vertical and speed profiles
for the segment being constructed in accordance with those updated
output values. In this regard, the expected altitude and speed
values for the aircraft 102 that are expected to result from the
preceding segment (e.g., the end points of the vertical and speed
profiles for the preceding segment) may be utilized to determine an
updated difference (if any) between the expected speed of the
aircraft 102 at the end of the preceding segment and the targeted
speed for the aircraft 102 at that location according to the
optimal speed profile for originally-planned reference descent
strategy and an updated difference (if any) between the expected
altitude of the aircraft 102 at the end of the preceding segment
and the targeted altitude for the aircraft 102 at that location
according to the optimal vertical profile for originally-planned
reference descent strategy. Thus, as the preceding segments reduce
the deviation from the originally-planned reference descent
strategy, the energy management parameter values used to construct
the recommended flight path may vary as the recommended flight path
gets closer to intercepting the reference descent strategy.
[0045] In a similar manner as described above for the initial
segment, the trajectory generator 210 utilizes one or more
aerodynamic models to model or otherwise predict the performance of
the aircraft along each respective segment of the recommended
flight path as a function of the expected aircraft gross weight at
the start of the segment, the expected fuel remaining at the start
of the segment, and any forecasted and/or expected meteorological
conditions along the segment, and then varies or otherwise
optimizes the vertical and speed profiles for the respective
segment that satisfy the constraining energy management parameter
values output by the variable energy management systems 212, 214,
216 for that segment. In this manner, the trajectory generator 210
incrementally and iteratively constructs segments for the
recommended flight path forward from the initial aircraft energy
state and initial aircraft location to progressively reduce
deviations between the expected aircraft energy state and the
targeted energy state until the speed and altitude deviations reach
zero, thereby indicating that the recommended flight path has
recaptured the reference descent strategy.
[0046] Still referring to FIG. 3, after determining vertical and
speed profiles for the segments that define the recommended flight
path for recapturing the reference descent strategy, the variable
energy management process 300 generates or otherwise provides an
output indicative of the recommended flight path (task 310). For
example, in one or more embodiments, the FMS 116, 202 generates or
otherwise provides a graphical representation of the vertical
profile and the speed profile for the recommended flight path on
the display device 104, which, in turn, may be utilized by a pilot
to manually fly the aircraft 102 to recapture the reference descent
strategy. In this regard, the displayed graphical representation of
the recommended flight path depicts the different segments that
make up the recommended flight path on the respective vertical and
speed profile displays, where the respective slopes of the vertical
profile and/or the speed profile of the respective segments may
vary from one to another to reflect the variable energy management
parameter value(s) for the respective segment. In some embodiments,
where a pilot engages or otherwise activates an autonomous
operating mode, such as a VNAV operating mode, the FMS 116, 202
outputs or otherwise provides the vertical profile and the speed
profile for the recommended flight path to the FCS 118, which, in
turn, autonomously operates the aircraft 102 in accordance with the
vertical and speed profiles for the different segments of the
recommended flight path. In this regard, the subject matter
described herein may be utilized to autonomously recapture an
originally-planned and previously-optimized descent strategy
computed by the FMS 116, 202 to restore operation with the desired
cost index or cost optimization.
[0047] FIG. 4 is a graph 400 depicting a graphical representation
of a vertical profile 402 for a recommended flight path constructed
in accordance with the variable energy management process 300 and
with a graphical representation of a speed profile 404 for a
recommended flight path constructed in accordance with the variable
energy management process 300 with respect to the distance to go
before reaching a destination airport 403. The graph 400 also
includes graphical representations of an optimal vertical profile
406 and an optimal speed profile 408 corresponding to the reference
descent strategy en route to the airport 403 that was previously
computed and optimized by the FMS 116, 220 and configured to
satisfy an upcoming AT altitude constraint 401 in advance of the
airport 403. Based on the altitude difference 410 between the
current aircraft altitude and the target aircraft altitude
according to the optimal vertical profile 406 indicating the
aircraft altitude is too high (or above the target altitude) and
the speed difference 412 between the current aircraft speed and the
target aircraft speed according to the optimal speed profile 408
indicating the aircraft 102 is flying too fast, the variable energy
management process 300 identifies the deceleration rate energy
management strategy for reducing the speed difference 412 and the
variable energy sharing energy management strategy for reducing the
altitude difference 410 (e.g., task 306).
[0048] Referring to FIG. 4 with continued reference to FIGS. 1-3,
in a similar manner as described above, for the initial segment 420
of the recommended flight path, the trajectory generator 210 inputs
or otherwise provides information characterizing the current state
of the aircraft 102 at the start of the segment to the deceleration
rate manager 214 and the energy sharing manager 216. Based on the
initial input information, the deceleration rate manager 214
calculates or otherwise determines a maximum deceleration rate for
the initial segment 420 and provides that initial deceleration rate
value to the trajectory generator 210. Similarly, the variable
energy sharing management system 216 calculates or otherwise
determines an energy sharing ratio for the relationship between the
reduction of potential energy over the upcoming segment and the
reduction of kinetic energy over the upcoming segment and provides
that initial energy sharing ratio value to the trajectory generator
210. The trajectory generator 210 utilizes the constraining
deceleration rate value provided by the deceleration rate manager
214 and the constraining energy sharing ratio value provided by the
energy sharing manager 216 to construct or otherwise generate
corresponding speed and altitude profiles for the initial segment
420. In this regard, the trajectory generator 210 optimizes flight
path angle and the speed profile for the initial segment 420 to
achieve the energy sharing ratio output by the energy sharing
manager 216 given the deceleration rate output by the deceleration
rate manager 214 using the appropriate drag configuration(s) for
the initial segment 420, the current aircraft gross weight at the
start of the initial segment 420, the current fuel remaining at the
start of the initial segment 420, and any forecasted and/or
expected meteorological conditions along the initial segment
420.
[0049] After determining vertical and speed profiles for the
initial segment 420, the trajectory generator 210 iteratively
repeats by constructing a second segment 430 forward from the end
of the initial segment 420. In this regard, the trajectory
generator 210 may utilize aerodynamic models to predict, estimate,
or otherwise determine the expected gross weight of the aircraft
102 and/or the expected fuel remaining onboard the aircraft 102 at
the end of the preceding initial segment 420. The trajectory
generator 210 may utilize the vertical profile and speed profile
constructed for the initial segment 420 determine an updated speed
difference 424 between the expected speed of the aircraft 102 at
the start of the second segment 430 and the targeted speed at that
location according to the optimal speed profile 408 for
originally-planned reference descent strategy, and the updated
altitude difference 422 between the expected altitude of the
aircraft 102 at the start of the second segment 430 and the
targeted altitude according to the optimal vertical profile
406.
[0050] The trajectory generator 210 inputs or otherwise provides
information characterizing the expected state of the aircraft 102
at the start of the second segment 430 (e.g., the expected altitude
difference 422, the expected speed difference 424, the expected
gross weight and/or fuel remaining, the expected drag
configuration, etc.) to the deceleration rate manager 214 and the
energy sharing manager 216, which, in turn, provide updated maximum
deceleration rate and energy sharing ratio values for the second
segment 430. In this regard, the updated variable energy management
parameter values are influenced by the expected deviations 422, 424
from the optimal descent profiles 406, 408, which are different
from the initial deviations 410, 412, and accordingly, the
constraining values for the identified variable energy management
parameters utilized to construct the second segment 430 may vary
from the variable energy management parameter values used to
construct the initial segment 420. As a result, the slopes of the
optimized vertical and speed profiles for the second segment 430 to
achieve the updated constraining values may vary from the optimized
vertical and speed profiles for the preceding segment 420 of the
recommended flight path. For example, as depicted in FIG. 4, the
second segment 430 may descend at a steeper flight path angle than
was used for the initial segment 420, but the speed may decelerate
slower over the second segment 430 than the initial segment
420.
[0051] In the illustrated embodiment of FIG. 4, the recommended
flight path composed of first and second segments 420, 430
intersects or otherwise intercepts the optimal vertical profile 406
at the AT altitude constraint 401 thereby ensuring the aircraft 102
satisfies the AT altitude constraint 401, while also intersecting
or otherwise intercepting the optimal speed profile 408 in advance
of at the AT altitude constraint 401, thereby allowing the aircraft
102 to recapture the reference descent strategy. As a result, the
aircraft 102 can proceed from the AT altitude constraint 401 en
route to the airport 403 in accordance with the descent strategy
that is optimized to achieve the desired cost and satisfy any
subsequent constraints (e.g., altitude, speed, stabilization,
and/or the like). In this regard, it should be noted that although
FIG. 4 depicts a simplified scenario that includes only two
segments 420, 430, in practice, the recommended flight path may
include any number of segments having any desired length.
[0052] As described above, after completing construction of the
recommended flight path that recaptures the reference descent
strategy, the FMS 116, 202 and/or the variable energy management
process 300 may be configured to display or otherwise present the
graph 400 of the variable energy management vertical and speed
profiles 402, 404 constructed for the segments 420, 430 of the
recommended flight path on the display device 104. In this regard,
the displayed graph 400 may also include a graphical representation
440 of the aircraft 102 at the current aircraft altitude with
respect to a graphical representation of the optimal vertical
profile 406 to provide the pilot with situational awareness of the
current altitude deviation 410 and the recommended sequence of
flight path angles for recapturing the optimal vertical profile
406. The graphical representation of the recommended recapture
speed profile 404 for the recommended flight path may also be
depicted with respect to the graphical representation of the
optimal speed profile 408 to provide the pilot with situational
awareness of the current speed deviation 412 and the recommended
sequence of deceleration. The graph 400 depicted on the display
device 104 may also include graphical indicia of the variable
energy management strategies identified by the variable energy
management process 300 and utilized to construct the recommended
profiles 402, 404 (e.g., variable deceleration rate and variable
energy sharing). Additionally, although not illustrated in FIG. 4,
in practice, any earlier drag configuration changes that are
indicated, identified, or otherwise recommended by the identified
variable energy management systems 214, 216 may also be displayed
or otherwise presented to the pilot on the graph 400, thereby
providing the pilot with situational awareness of when a drag
configuration change is recommended or required for recapturing the
optimal descent strategy. In some embodiments, the pilot may enable
an autonomous operating mode, such as a VNAV descent, which, in
turn results in the FCS 118 utilizing the vertical and speed
profiles 402, 404 constructed by the variable energy management
process 300 to autonomously operate the aircraft 102 (e.g., via
commands provided to the autopilot and thrust manager) to recapture
the optimal descent profiles 406, 408. Once the aircraft 102
recaptures the original optimal descent strategy, the FCS 118 may
transition from using variable energy management strategies to
autonomous operation in accordance with the optimal descent
strategy.
[0053] FIG. 5 is another embodiment of a graph 500 depicting a
graphical representation of a vertical profile 502 for a
recommended flight path constructed in accordance with the variable
energy management process 300 and with a graphical representation
of a speed profile 504 for a recommended flight path constructed in
accordance with the variable energy management process 300 with
respect to an optimal vertical profile 506 and an optimal speed
profile 508 corresponding to the reference descent strategy en
route to an airport 503 that was previously computed and optimized
by the FMS 116, 220 and configured to satisfy an upcoming AT
altitude constraint 501 in advance of the airport 503. Based on the
altitude difference 510 between the current aircraft altitude and
the target aircraft altitude according to the optimal vertical
profile 506 indicating the aircraft altitude is too low (or below
the targeted altitude) and the speed difference 512 between the
current aircraft speed and the target aircraft speed according to
the optimal speed profile 508 indicating the aircraft 102 is flying
too fast, the variable energy management process 300 identifies the
variable deceleration rate energy management strategy for reducing
the speed difference 512 and the variable vertical speed strategy
for reducing the altitude difference 510 to restore the aircraft
102 to the optimal vertical profile 506 (e.g., task 306).
[0054] Referring to FIG. 5 with continued reference to FIGS. 1-3,
in a similar manner as described above, for the initial segment 520
of the recommended flight path, the trajectory generator 210 inputs
or otherwise provides information characterizing the current state
of the aircraft 102 at the start of the segment to the vertical
speed manager 212 and the deceleration rate manager 214. Based on
the initial input information, the deceleration rate manager 214
calculates or otherwise determines a maximum deceleration rate for
the initial segment 520 and provides that initial deceleration rate
value to the trajectory generator 210. Similarly, the vertical
speed manager 212 calculates or otherwise determines a minimum
descent rate (or downward vertical speed) for the aircraft 102
given the maximum deceleration rate and the other input information
and provides that constraining vertical speed value to the
trajectory generator 210. The trajectory generator 210 utilizes the
constraining vertical speed value provided by the vertical speed
manager 212 and the constraining deceleration rate value provided
by the deceleration rate manager 214 to construct or otherwise
generate corresponding speed and altitude profiles for the initial
segment 520. In this regard, the trajectory generator 210 optimizes
flight path angle and the speed profile for the initial segment 520
to achieve the vertical speed value output by the vertical speed
manager 212 given the deceleration rate output by the deceleration
rate manager 214 using the appropriate drag configuration(s) for
the initial segment 520, the current aircraft gross weight at the
start of the initial segment 520, the current fuel remaining at the
start of the initial segment 520, and any forecasted and/or
expected meteorological conditions along the initial segment
520.
[0055] After determining vertical and speed profiles for the
initial segment 520, the trajectory generator 210 iteratively
repeats by constructing a second segment 530 forward from the end
of the initial segment 520. As described above, the trajectory
generator 210 utilizes the vertical profile and speed profile
constructed for the initial segment 520 determine an updated speed
difference 524 between the expected speed of the aircraft 102 at
the start of the second segment 522 and the targeted speed at that
location according to the optimal speed profile 508 for
originally-planned reference descent strategy, and the updated
altitude difference 522 between the expected altitude of the
aircraft 102 at the start of the second segment 522 and the
targeted altitude according to the optimal vertical profile 506.
The trajectory generator 210 inputs or otherwise provides
information characterizing the expected state of the aircraft 102
at the start of the second segment 530 (e.g., the expected altitude
difference 522, the expected speed difference 524, the expected
gross weight and/or fuel remaining, the expected drag
configuration, etc.) to the vertical speed manager 212 and the
deceleration rate manager 214, which, in turn, provide updated
maximum deceleration rate and constraining vertical speed values
for the second segment 530. As described above, by virtue of the
constraining variable energy management parameter values varying on
a per-segment basis, the slopes of the optimized vertical and speed
profiles for the second segment 530 to achieve the updated
constraining values may vary from the optimized vertical and speed
profiles for the preceding segment 520 of the recommended flight
path. For example, as depicted in FIG. 5, the second segment 530
may descend at a shallower flight path angle than was used for the
initial segment 520, and the speed may decelerate slower over the
second segment 530 than the initial segment 520.
[0056] In the illustrated embodiment of FIG. 5, the recommended
flight path composed of first and second segments 520, 530
intersects or otherwise intercepts the optimal vertical profile 506
at the AT altitude constraint 501 thereby ensuring the aircraft 102
satisfies the AT altitude constraint 501, while also intersecting
or otherwise intercepting the optimal speed profile 508 in advance
of at the AT altitude constraint 501, thereby allowing the aircraft
102 to recapture the reference descent strategy. Again, it should
be noted that although FIG. 5 depicts a simplified scenario that
includes only two segments 520, 530, in practice, the recommended
flight path may include any number of segments having any desired
length.
[0057] As described above, after completing the recommended flight
path, the FMS 116, 202 and/or the variable energy management
process 300 may be configured to display or otherwise present the
graph 500 of the variable energy management vertical and speed
profiles 502, 504 constructed for the segments 520, 530 of the
recommended flight path on the display device 104. The graph 500
depicted on the display device 104 may also include graphical
indicia of the variable energy management strategies identified by
the variable energy management process 300 and utilized to
construct the recommended profiles 502, 504 (e.g., variable
vertical speed and deceleration rate). Additionally, although not
illustrated in FIG. 5, in practice, any delayed drag configuration
changes that may be indicated, identified, or otherwise recommended
by the identified variable energy management systems 212, 214 may
also be displayed or otherwise presented to the pilot on the graph
500. When an autonomous operating mode such as a VNAV descent is
activated or enabled, the FMS 116, 202 provides the recommended
vertical and speed profiles 502, 504 constructed by the variable
energy management process 300 to the FCS 118, with the FCS 118
utilizing the vertical and speed profiles 502, 504 to autonomously
operate the aircraft 102 to recapture the optimal descent profiles
506, 508.
[0058] By virtue of the subject matter described herein, a pilot
may be apprised of how the aircraft can be operated to recapture an
originally-planned and cost-optimized descent strategy when it may
not otherwise be apparent to the pilot whether or how the aircraft
can be operated to vary the energy state of the aircraft to satisfy
upcoming constraints and restore operation in accordance with the
optimized descent strategy. Additionally, the variable energy
management strategy allows an autonomous operating mode to be
activated or otherwise enabled to autonomously return the aircraft
to the optimal descent strategy, resulting in improved cost
management and ensuring safety and compliance with applicable
constraints.
[0059] For the sake of brevity, conventional techniques related to
flight management, flight controls, flight planning, air traffic
control, energy management, autopilot, autothrottle, or other
automation, navigation systems, inertial reference systems,
graphics and image processing, avionics systems, and other
functional aspects of the systems (and the individual operating
components of the systems) may not be described in detail herein.
Furthermore, the connecting lines shown in the various figures
contained herein are intended to represent exemplary functional
relationships and/or physical couplings between the various
elements. It should be noted that many alternative or additional
functional relationships or physical connections may be present in
an embodiment of the subject matter.
[0060] The subject matter may be described herein in terms of
functional and/or logical block components, and with reference to
symbolic representations of operations, processing tasks, and
functions that may be performed by various computing components or
devices. It should be appreciated that the various block components
shown in the figures may be realized by any number of hardware
components configured to perform the specified functions. For
example, an embodiment of a system or a component may employ
various integrated circuit components, e.g., memory elements,
digital signal processing elements, logic elements, look-up tables,
or the like, which may carry out a variety of functions under the
control of one or more microprocessors or other control devices.
Furthermore, embodiments of the subject matter described herein can
be stored on, encoded on, or otherwise embodied by any suitable
non-transitory computer-readable medium as computer-executable
instructions or data stored thereon that, when executed (e.g., by a
processing system), facilitate the processes described above.
[0061] The foregoing description refers to elements or nodes or
features being "coupled" together. As used herein, unless expressly
stated otherwise, "coupled" means that one element/node/feature is
directly or indirectly joined to (or directly or indirectly
communicates with) another element/node/feature, and not
necessarily mechanically. Thus, although the drawings may depict
one exemplary arrangement of elements directly connected to one
another, additional intervening elements, devices, features, or
components may be present in an embodiment of the depicted subject
matter. In addition, certain terminology may also be used herein
for the purpose of reference only, and thus are not intended to be
limiting.
[0062] The foregoing detailed description is merely exemplary in
nature and is not intended to limit the subject matter of the
application and uses thereof. Furthermore, there is no intention to
be bound by any theory presented in the preceding background, brief
summary, or the detailed description.
[0063] While at least one exemplary embodiment has been presented
in the foregoing detailed description, it should be appreciated
that a vast number of variations exist. It should also be
appreciated that the exemplary embodiment or exemplary embodiments
are only examples, and are not intended to limit the scope,
applicability, or configuration of the subject matter in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing an
exemplary embodiment of the subject matter. It should be understood
that various changes may be made in the function and arrangement of
elements described in an exemplary embodiment without departing
from the scope of the subject matter as set forth in the appended
claims. Accordingly, details of the exemplary embodiments or other
limitations described above should not be read into the claims
absent a clear intention to the contrary.
* * * * *